Resurection incoming...
I realize it's an old thread, but I don't see too many new threads popping up these days with Civ3 so let's beat this dead horse shall we?
The reason this strategy can be effective is that it is incredibly efficient... someone mentioned earlier how the slider works, that it is done city-by-city which means the fractions don't always (or even often) work out accurately. Therefore the most efficient use of the slider will always be at 100% or 0%. 100% is not impossible to achieve but it is difficult to maintain, yet 0% is easy to maintain. Then take into account your multiplier buildings, specifically the first available ones; library and marketplace. With this strategy building a marketplace yields the greatest possible return, while at the same time your civ has no need to build libraries. In a science oriented strategy you obviously need libraries, but you're probably going to need those marketplaces too. (for the multiplier in case you cant quite reach 100%, or for the happiness bonus from luxuries) So that's 180 shields to build both of these in your important, or all, cities. By playing this brokering strategy you eliminate the need for science buildings completely while at the same time getting the MOST from your marketplaces. It is easier to completely focus on either science or taxes instead of constantly mixing a little bit of both. The problem is as I mentioned if you focus on science you still need the marketplaces, whereas if you focus on taxes you don't need the libraries. All that being said, in my experience this strategy (the way I play it at least) works only on the higher difficulties (emperor and above) because IMO the AI doesn't research fast enough for me. On the lower difficulties getting and keeping a tech lead isn't hard at all, so you're better off bee-lining a military tech and conquering the world.
